Anyone who shares the passion for peregrine falcons would understand, even if it were his lens I dropped in the beaver pond.

I was trying for pictures of wood ducks paddling around the nest boxes we have put up for them along a marshy arm of the Patuxent River in Southern Maryland. It was the third weekend I had spent in the photo blind, during which I had gotten plenty of pictures of wood ducks and plenty of shots of the nest boxes, but none of wood ducks and the nest boxes, which was what the editor had specified.

Part of the problem was the cameras, numbering three: one loaded with slow Kodachrome, another with fast Ektachrome and the third with variable-speed black- and-white. Real photographers manage to manage as many as half a dozen cameras at a time, but I had blown several chances by grabbing the wrong one or freezing indecisively with a lens in either hand while the birds zipped in and out of range.

Most of the morning of the sixth day in the blind had been spent watching a pair of woodies -- he gorgeous in his Joseph's coat, she splendid in muted brown and buff with Cleopatra eyestreaks -- fooling around in the reeds on the other side of the pond. Really fooling around: either they were mating or he was trying to drown her.

Twoscore times they drifted towards me as though to take possession of a nest box, and twoscore times I frantically switched to shorter lenses as they neared, only to see them open the range again. The blind was hot and cramped and I was nearly strangled from the tobacco dust sifting out of the burlap with which it is covered (courtesy of the Hughesville Farmers Market).

Toward noon I stood up to stretch, and as I rose a peregrine falcon flushed from a nearby tree. It flew to another tree a hundred feet away, and I fumbled for the telephoto extender to double the power of the 70-210mm lens (courtesy of Canon USA). Just as it clicked into place the falcon took off again, straight toward me.

It lit on a branch six feet in front of my face and perched there looking placid and unfierce, as peregrines always seem to seem except while they are blasting ducks out of the sky or gulping the shreds.

Now, I had never seen a peregrine at six feet even in a zoo, and stood there foolishly going over the marks: yes, much too big for a merlin; yes, whiskers around the face; yes, full feathers down the legs . . . after some moments of this silly business it occurred to me to take a picture; but the only camera within reach was the one I had just put the doubler lens on.

Trying not to stare at the bird (a fixed gaze generally makes wild things nervous) or to move or make noise, I removed the doubler lens by feel, remounted the zoom and fumbled it into approximate focus before beginning to slowly raise the camera.

The peregrine seemed curious rather than alarmed as the machinery came into view above the apron of the blind ("Must be a hacked bird, it's so tame," I thought to myself) and cocked its head at me.

"What a picture," I exulted silently as the viewfinder reached my eye. At the same moment the doubler lens, still clamped in the spare fingers of my left hand, hit my chin and slipped from my sweaty grasp. The peregrine did not flush when the lens hit the floor of the blind, nor while it rolled noisily for several feet. It flushed when the lens found the one hole through which it could fit and fell with a splash into the pond.

All this while I was watching the peregrine through the viewfinder. He was nicely framed, every whisker in focus; before he took off he slowly spread his magnificent wings and paused briefly as I marveled. Not at any point did it occur to me to press the shutter. As he flew away I had the impression he was looking back over his shoulder.

I spoke to myself at length as I stripped and dove for the lens. Back in the blind, freezing, I wiped myself with what was available -- my clothes -- until I was dry and they were wet, and put them back on.

All this odd activity piqued the interest of the male woodie who had been teasing me all morning; he paddled up and posed by the nest box, perhaps in the hope that I would drop another lens.